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Gas Furnace Replacement -- Advice Requested

Hello everyone. I recently purchased a home in the Seattle area and have received the fun surprise of the furnace needing replacement. The goofballs before me replaced a failed 3-speed blower with a 2-speed, the electronic air filter is busted, and I've had to bypass a limit switch due to a failure there (don't worry, there are 2). All told to get this fixed, it's approaching $$$$. No thanks - a new unit sounds more reasonable.

My house is about 3700 sq feet with 20 registers. The existing system is a 15 yr old single stage Lennox rated at 120,000 BTU (if i read the label right of aga/cga=120000) with a programmable single stage Honeywell thermostat. I don't know what the efficiency rating is.

The foyer and living room on the entrance are two story, but everything else is 9' ceilings. We do have warm/cold spots in the house, but nothing unbearable. We moved here from OH, so it's not really cold here and we only ran the air conditioner 2 days last summer. I plan on selling the home in 8 years when the kids leave for college to go somewhere warm and sunny.

I've never bought a furnace before, so let the journey begin..

I've had two pretty well-known local installers come and provide bids -- the 1st recommended a York Affinity Modulating 80% Variable unit, rated at 120,000 btu's. He indicated the modulating feature would help better balance the heat in the house, while saving on gas and electric (lower voltage fan). This guy was a salesman to the core.

The 2nd company recommended a Bryant 2 stage 80% variable unit rated at 110,000 btu. This guy was a tech and not a sales guy (he's done some minor repair work on my existing furnace). He felt the current unit is oversized based on his calculations (sq feet and # of registers). I asked him about modulating furnaces, especially the York. His feedback was that modulating really isn't that much better than 2 stage and while he could quote me one, advised against it due to higher reliability issues. He shared he works on Yorks way more than Bryants.

Neither of these gentlemen conducted a "J load test" (I've been reading prior posts), but rather based their recommendations on area and registers. They both said a duct test would be done to determine if any leaks existed in the duct work, as part of the installation. I'm not sure if that's what is recommended or not. I will say both of them indicated they charge the same price for the furnace, regardless of BTU sizing.

So where I'm at now is a crossroads -- I really have no idea about this stuff, but want to get moving on the project. Our goal isn't to have the warmest home on the street, we would just like to have a tad lower bills and be a bit more comfortable than we are today. We can't afford the super system, but don't want to get the cheapest thing either. Looking to strike a good balance.

With that long story, it comes down to a few questions -- do I need to push these guys to come do a j load test then update the bids? And what about this modulating furnace stuff? Is it just marketing or is there some value there? For reference, contractor 1 is about $$$ under contractor 2 (or 10%). Any other advice (or suggestions on solid installers around Seattle)?

Thanks everyone for reading and if you're able to provide some feedback. I really appreciate your time and help in advance!
Ryan

I've never heard sizing the furnace off of the number of registers. Maybe the blower, but generally the A/C will dictate the blower size. Also one that I haven't heard before, "Btu size doesn't effect the price". That's priceless.

Both furnaces are good. If the York is that much less and you're concerned, get the 10 year labor protect plan. They are not expensive. The Bryant comes with a standard "E-Z" hi-efficiency filter. I would recommend one.

I've never heard sizing the furnace off of the number of registers. Maybe the blower, but generally the A/C will dictate the blower size. Also one that I haven't heard before, "Btu size doesn't effect the price". That's priceless.

Both furnaces are good. If the York is that much less and you're concerned, get the 10 year labor protect plan. They are not expensive. The Bryant comes with a standard "E-Z" hi-efficiency filter. I would recommend one.

In Seattle, I'd guess that the furnace will dictate blower size. No cooling load there. Not much heating load either. Pretty common in mild climate to get oversized by 2 or even 3x what you actually need.

I agree that the "BTU doesn't affect cost". I'd say off hand a 5-8% increase in cost for each step in size. So if you install a 100k instead of a 60k, you're looking at a 10-15% increase. That adds up.

A properly sized AC unit can use up to 30% less energy than a oversized unit, especailly on hte same sized ductwork. Meaning that a basic 13SEER can outperform a oversized 20SEER system, expecially in hot weather where their actual power consumtion ratings are a lot closer and hte smaller unit will run almsot continously.... whicg is good.

Thanks all for the feedback thus far -- really helpful! To answer the above question, I'm not doing anything bout the AC right now. That part of the system is working fine, but quite honestly, AC in the pacific northwest is really not necessary as it just doesn't get hot enough. Running just the blower with windows open gets the job done just fine. (At least that was our experience this past summer that was supposedly way hotter than prior years.) We just moved here in July coming from OH, then south Louisiana before that, so we're used to real heat.

I could have been wrong about them using the registers to size the system, but those were just the only two questions they asked Neither of them walked thru the house at all. They both recommended a 5 ton blower (which is what is installed today).

I think I'll check the directory here for another contractor to get a 3rd opinion, stipulating the j load test is required. From spending time on this forum, I can at least sound a little smarter.

I'll also have to do research on this media filter cabinet suggestion -- i'm not familiar with what that is...

Can anyone offer opinions on the value of the modulating furnace over the 2-stage in milder climates? In this case, the modulating york is less than the 2 stage by 10%, but is less more ?

Because you live an a location with relatively mild winter climate, I think a two stage var speed furnace would be fine. It should have a true two stage thermostat that controls the stages rather than operate off timer that will leave you on high stage whether you need it or not. You will need to decide about 80% eff or 95+% eff on furnace. I know your electric rates are low so even a HP in a DF application might be something to consider.

As mentioned in my post, two systems will give you best control and comfort. If not two systems, perhaps one system with zoning controls. Discuss with your dealer.

Thx for the info. I am figuring on an 80% eff furnace b/c of the lower upfront cost, the mild winters, and the fact we'll be in the house less than 10 years. I'll talk to them about two systems and or zoning. The key element tho is that I don't want to increase our gas prices due to increased comfort. We keep the house on the cooler side just to avoid the massive gas bills (usually set to 68F and keep blankets handy). Hoping to see somewhat of a reduction in the bills with the new unit. This replacement was not on the short-term plan, so trying to keep our costs low.

I assume by HP, you mean heat pump. I did ask one of the dealers about this scenario, and he indicated it would double to triple the upfront cost + install, so heavily advised against it. Not sure if that's consistent with your thinking.

Because you live an a location with relatively mild winter climate, I think a two stage var speed furnace would be fine. It should have a true two stage thermostat that controls the stages rather than operate off timer that will leave you on high stage whether you need it or not. You will need to decide about 80% eff or 95+% eff on furnace. I know your electric rates are low so even a HP in a DF application might be something to consider.

As mentioned in my post, two systems will give you best control and comfort. If not two systems, perhaps one system with zoning controls. Discuss with your dealer.

IMO

The larger furnaces with VS motors will always come with a 5 ton blower. Doesn't the Bryant 2-stage VS work off of algorithms? Then no need for a 2 stage stat. Regarding all the work for a Manual J........what is he going to save on a 90,000 Btu Bryant or a 100,000 Btu York? He has a 120,000 (old) Lennox now. It's probably 30+" wide and 50+'' tall. The fore mentioned furnaces are 21" wide and 34" tall. The owner will freak out. LOL.

Definitely get a load calc ('manual j') don to get the proper size furnace. As the others mentioned, oversizing is a huge efficiency killer. If the house is well insulated & sealed you may be able to drop down to an 80k unit. Do you know what size the AC is? This may be a deciding factor in selecting the furnace on order to get the blower needed for the AC. The modulating unit will be sightly more comfortable and quieter as it can run all the way down to 30% of maximum firing rate, and the continuous fan can be as low as 15-17% which uses very little energy, is super quiet, and helps to even out the temps throughout the house. If you have to oversize to get the bigger blower for the AC, the modulating furnace would be the better choice.

As far as brands go, don't worry too much about it. All the major manufacturers are pretty equal quality wise when comparing similar models. What really makes or breaks a system is proper sizing and installation. While I do really like the Carrier Infinity controller, it's really only worth it if you are going for all new infinity equipment (furnace AND AC or HP). The York communicating controller is also a good unit, and I think their secondary heat exchangers are a better design. Also their great to deal with for any warranty issues. In the end, do your research on the contractors & check references from previous customers and find one you feel comfortable with.

And just FYI, I worked for a Carrier dealer for 10 years and have been working for a York dealer for the last 1.5. The brands sold had nothing to do with switching. Happy hunting!